This invention relates generally to a device that removes thermal build-up generated from the operation of electrical components on a circuit board and more particularly, to the removal of thermal build-up from the operation of electrical components on a circuit board utilizing a forced air stream.
It is known that energized electrical components positioned on a circuit board generate a significant amount of heat. In most industries, such as the telecommunications industry, there is a need to place higher output electronic devices on already congested circuit boards. Higher clock speed and higher density interconnects lead inevitably to higher power densities on a chip. The resultant byproducts of the high output devices are high levels of thermal dissipation from the chip or component and the immediately surrounding atmosphere to the component. These high levels of thermal energy being dissipated to the immediate surrounding environment are problematic to maintaining effective operation and optimum life of surrounding electrical components.
Higher output devices are known to utilize an increased number of multi-chip modules, increased surface circuit board mounting technology such as mezzanine boards, and reduced package dimensions all of which exacerbate the problem of the undesirable thermal build-up from the thermal dissipation of energized electrical components residing on the circuit board(s). With power per unit area on circuit boards as much as quadrupling over less than the past decade, thermal design issues have arisen that as recently as five years ago were not even comprehended or contemplated.
As mentioned above, a contributing problem to thermal build-up is the utilization of mezzanine arranged or stacked circuit boards. The increased use of mezzanine boards has come about with the increase of clock speeds and shorter lead traces, the circuit designers have needed to shorten the electrical path between components enabling quicker response time of the electronics. The negative side of these arrangements is there is an increase of power density from the electrical components on the circuit boards thereby releasing heat energy in a relatively smaller area. Therefore, there is an increasing need to remove this thermal energy away from the proximity of the electrical components and not allow the dissipated energy to build-up on localized areas of the circuit boards and the surrounding electrical components. Failure to remove the undesirable thermal build-up can place the die of an integrated circuit component at critical elevated temperatures that either temporarily or permanently damage the components.
Another problem has been created with the closer positioning of the circuit boards to one another in a stacked or mezzanine arrangement. This problem is based on radiation energy generated from high-energy dies on a circuit board. Normally a circuit board with a centralized die will experience lower temperatures at the edges of the circuit board and greater temperatures at the location of the die. Radiation may be a major heat transfer mechanism for outer space applications but is generally negligible where the circuit board is positioned in a forced air convection system. However, with closer positioning of the components within a mezzanine arrangement of circuit boards, radiation of energy from these high energy components will further lead to thermal build-up.
Moreover, these compact circuit arrangements pose yet additional problems. Regardless of the components being positioned within a forced air stream, the tight arrangements of the components increases the air stream flow resistance thereby blocking the air flow and reducing its thermal dissipation capabilities based on convection from the forced air stream.
As a result of utilizing higher energy components that are more densely arranged upon a circuit board and positioning multiple circuit boards in closer proximity to one another, thermal build-up has become a problem, regardless of the use of forced air streams flowing over the circuit boards.
The problems noted above are resolved by providing the apparatus and method of the present invention.
The invention provides apparatus for removal of thermal energy emitted from at least one electrical component positioned on a circuit board, in which a forced air stream is provided in a direction to flow over the circuit board and the at least one electrical component including a rod having an elongated dimension, in which the elongated dimension is positioned transverse to the direction of the forced air stream, upstream from the at least one electronic component and spaced apart from a plane defined by the circuit board.
This invention also provides a method for removal of thermal energy emitted by at least one electrical component positioned on a circuit board which has a forced air stream provided and directed to flow over the circuit board and the at least one of the electrical components including the steps of providing a rod having an elongated dimension and positioning the rod in the forced air stream with the elongated dimension transverse to the direction of the forced air stream, upstream to at least one of the electrical components and spaced apart from a plane defined by the circuit board. Turbulence is imparted to the forced air stream by the rod and thereby provides a movement of the air stream that enhances the removal of heat energy emitted by the activated electrical component.